"Germainaia geayi is known only from 2.5 specimens with the vague locality "Madagascar." The species was originally described as "Unio (Nodularia) geayi" by Germain (1911). Most subsequent treatments, however, have put G. geayi in the genus Coelatura. Unio, Nodularia, and Coelatura are all genera assigned to the family Unionidae. However, we aren't completely convinced that the available material actually belongs to that family.

"Upon first inspection of the type when we were in Paris in 2006, that specimen struck us as more similar to a hyriid, like one might find in Australia or New Zealand (such as Hyridella depressa). While members of the Unionidae and the Hyriidae can be readily distinguished based upon their soft-anatomy, we have had trouble when it comes to family-level shell synapomorphies.

"Given the scanty material available for G. geayi and the conflicts it presents to going biogeographical hypotheses, we regard Germainaia as incertae sedis at the family level."

For more information about Germainaia and the freshwater mussels of Madagascar:

Graf, D.L. & K.S. Cummings. 2009. Actual and alleged freshwater mussels (Mollusca: Bivalvia: Unionoida) from Madagascar and the Mascarenes, with description of a new genus, Germainaia. Proceedings of the Academy of Natural Sciences of Philadelphia 158: 221-238.